fix: query implementation

README.md

@@ -16,7 +16,7 @@ To add and install this package as a dependency of your project, run `poetry add
 ### A simple example:
 ```python
 from pydantic import BaseModel, EmailStr
-from querytyper import MongoModelMetaclass, MongoQuery
+from querytyper import MongoFilterMeta, MongoQuery
 
 class User(BaseModel):
     """User database model."""
@@ -25,7 +25,7 @@ class User(BaseModel):
     age: int
     email: EmailStr
 
-class UserFilter(User, metaclass=MongoModelMetaclass):
+class UserFilter(User, metaclass=MongoFilterMeta):
     """User query filter."""
 
 query = MongoQuery(

pyproject.toml

@@ -32,6 +32,8 @@ pytest-clarity = ">=1.0.1"
 pytest-mock = ">=3.10.0"
 pytest-xdist = ">=3.2.1"
 ruff = ">=0.1.3"
+pymongo = "^4.6.1"
+mongomock = "^4.1.2"
 
 [tool.poetry.group.dev.dependencies]  # https://python-poetry.org/docs/master/managing-dependencies/
 cruft = ">=2.14.0"

src/querytyper/__init__.py

@@ -1,9 +1,9 @@
 """querytyper package."""
-from querytyper.mongo import MongoModelMetaclass, MongoQuery, exists, regex_query
+from querytyper.mongo import MongoFilterMeta, MongoQuery, exists, regex_query
 
 __all__ = [
     "MongoQuery",
-    "MongoModelMetaclass",
+    "MongoFilterMeta",
     "regex_query",
     "exists",
 ]

src/querytyper/mongo/__init__.py

@@ -1,9 +1,10 @@
 """querytyper package."""
-from querytyper.mongo.query import MongoModelMetaclass, MongoQuery, exists, regex_query
+from querytyper.mongo.meta import MongoFilterMeta
+from querytyper.mongo.query import MongoQuery, exists, regex_query
 
 __all__ = [
     "MongoQuery",
-    "MongoModelMetaclass",
+    "MongoFilterMeta",
     "regex_query",
     "exists",
 ]

src/querytyper/mongo/meta.py

@@ -0,0 +1,53 @@
+"""MongoFilterMeta implementation."""
+from typing import Any, Dict, Tuple, Type
+
+from pydantic import BaseModel
+from pydantic.main import ModelMetaclass
+
+from querytyper.mongo.query import QueryField
+
+DictStrAny = Dict[str, Any]
+
+
+class MongoFilterMeta(ModelMetaclass):
+    """
+    Metaclass for query models.
+
+    Use this metaclass to define query models.
+
+    Example
+    -------
+    ```python
+    class TransactionFilter(Transaction, metaclass=MongoFilterMeta):
+        pass
+    ```
+    """
+
+    def __new__(
+        cls,
+        name: str,
+        bases: Tuple[Type[Any]],
+        namespace: DictStrAny,
+    ) -> Type["MongoFilterMeta"]:
+        """Override new class creation to set query fields as class attributes."""
+        # check exactly one base class
+        if len(bases) > 1:
+            raise TypeError("MongoFilterMeta does not support multiple inheritance")
+        if len(bases) < 1:
+            raise TypeError(
+                "The class with metaclass MongoFilterMeta requires a base class that inherits from BaseModel"
+            )
+        # check the base class is a subclass of BaseModel
+        if not issubclass(bases[0], BaseModel):
+            raise TypeError(f"The base class must inherit from {BaseModel.__qualname__}")
+        base_model_cls: Type[BaseModel] = super().__new__(cls, name, bases, namespace)
+        for field_name, model_field in base_model_cls.__fields__.items():
+            setattr(
+                cls,
+                field_name,
+                QueryField[model_field.type_](  # type: ignore[name-defined]
+                    name=field_name,
+                    field_type=model_field.type_,
+                ),
+            )
+        return cls